Mechanism for use in a well bore



Feb 14, 1967 E. l.. MEDFoRD, .1R

MECHNISM FOR USE IN A WELL BORE 2 Sheets-Sheet l Filed Oct. 19, 1964INVENTOR Feb. 14, 1967 E. L.. MEDFQRD, JR

MECHANISM FOR USE IN A WELL BORE 2 Sneets-Sheet 2 Filed Oct. 19, .T964

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INVENTOR ERSKIN l.. MEDI-'ORD ,JR

United States Patent Patented Feb. lll, i957 3,303,884 MECHANHSM FR USEHN A WELL BQRE Erslrin L. Medford, Jr., Duncan, Ulrla., assigner toHalliburton Company, Duncan, Okla., a corporation of Delaware Filed Oct.i9, 1964, Ser. No. 404,394 8 Claims. (Cl. 166-63) This invention relatesto a mechanism for use in a well bore. In particular, it relates to aforce transmitting mechanism adapted to effect the eflcient actuation ofapparatus such as packers.

A variety of setting tools have heretofore been developed to facilitatethe setting or actuation of devices such as packers within a well borein response t-o a setting force remotely generated within the well bore.In general, however, such setting mechanisms have not made the mosteffective utilization of the available setting force during portions ofthe apparatus setting cycle when different levels of force could be mostefficiently employed. In addition, previously known setting tools haveoften failed to cause movable, apparatus setting members to move at themost effective rates during portions of the apparatus setting oractuating cycle.

It is an object of the present invention to provide apparatus which, inresponse to available force, effectively varies this force during thecycle of setting an apparatus within a -well bore to obtain improvedefiiciency.

A related, principal object of the invention is to provide such anapparatus which varies the rate of movement of apparatus setting oractuating members during a setting cycle so as to obtain improvedsetting eiliciency.

A more specific object of the invention is to provide an apparatus foruse in a well bore which, in response to force remotely generated withina well bore, applies a relatively low setting force to an apparatusduring the portion of the setting cycle when relatively low force isrequired and which applies relatively greater setting force whenrelatively greater force is required.

A similar, more specific object of the invention is to provide anapparatus for use within a well bore which, in response to a forceremotely generated within the well bore, causes a movable apparatussetting or actuating member to move at a relatively rapid rate duringthe first portion of the setting cycle where a low setting force isrequired and to move at a relatively slower rate during a later portionof the setting cycle when greater setting force is required.

It is also an object of the invention to provide such apparatus whichmay be so configured as to have movable components exposed to thepressure of well bore fluids but which components may remainsubstantially pressure balanced and not adversely affected by suchpressure.

A still further object of the invention is to provide a fluid, forcetransmitting coupling between components of a force transmittingmechanism which may be automatically `supplied from well bore fluids asthe mechanism is lowered into a well bore.

In order to accomplish the foregoing objectives, there is presentedthrough this invention an apparatus for use in a well bore whichincludes force generating means having actuating means and which isoperable Within a well bore to move the actuating means. The apparatusmay further include a mechanism to be actuated within the well bore.Force transmitting means included in the apparatus are operativelydisposed between the actuating means and the mechanism to be actuated.The force transmitting means includes first means movable in response tomovement of the actuating means and second means movable in response tomovement of the first means and adapted to actuate the mechanism.Coupling means included in the force transmitting means operably connectthe rst and second means. The coupling means is adapted to cause thesecond means to initially move at a first rate more rapid than the rateof movement of the first means and thereafter move at a second rateslower than the first rate. The second means, while moving at the secondrate, transmits greater force to the mechanism than when moving at thefirst rate.

A particularly significant and independent aspect of the inventionresides in the particular structure of a force transmitting means. Thisstructure comprises first piston means and second piston means having atleast first and second, fluid reactive, piston head areas. Couplingmeans operatively connecting these piston means comprise first cylindermeans in which the first piston means is slidably received. The couplingmeans further includes second cylinder means in fluid communication withthe first cylinder means and in which the second piston means isslidably received. The second cylinder means has a rst portion adaptedto expose only the first, fluid reactive, piston head area of the secondpiston means to the pressure of fluid urged by the first piston meansfrom the first cylinder means into the second cylinder means during oneportion of the movement of the second piston means. The second cylindermeans further includes a second portion which is adapted to expose boththe first and second, fluid reactive, piston head areas of the secondpiston means to the pressure of fluid moved by the first piston meansfrom the first cylinder means into the second cylinder means duringanother portion of the movement of the second piston means. Gne of thepiston means is adapted to move in response to a force applied theretowithin a well bore. The other of the piston means is adapted to transmitforce to means to be actuated within the well bore.

In describing the invention reference will be made to a preferredembodiment shown in the drawings.

In the drawings:

FIGURE l provides a partially sectioned, schematic, vertical elevationview of an apparatus to be actuated within a well bore, which apparatusincludes a setting portion, a force transmitting portion, and a radiallyexpansible packer portion. FIGURE l illustrates the portions of theapparatus prior to the setting of the packer portion;

FIGURE 2 schematically illustrates the portions of the FIGURE lapparatus during the initial part of the setting of the packer portion;

FiGURE 3 schematically illustrates the disposition of the components ofthe FGURE l apparatus during the terminal part of the setting of thepacker portion;

FIGURE 4 provides an enlarged, sectioned, vertical elevational View ofoperating components of the force transmitting portion of the apparatusshown in FIG- URE l;

FIGURE 5 is a cross sectional view of the FIGURE 4 assembly as viewedalong the section line 5 5;

FIGURE 6 is a cross sectional view of the FIGURE 4 assembly as viewedalong the section line 6 6;

FIGURE 7 is a cross sectional view of the FIGURE 4 assembly as viewedalong the section line 7 7; and

FIGURE 8 is a fragmentary, schematic view of a portion of the FIGURE 4assembly illustrating representative increments of movement of oneannular piston corresponding to and resulting from increments ofmovement of another annular piston.

FIGURE 1 illustrates an apparatus which includes as its principalcomponents a force generating or setting tool portion 1, a forcetransmitting portion 2, and a mechanism to be actuated, i.e., packerportion 3.

As illustrated in FIGURE l, the overall apparatus may 3 be supportedwithin a well bore 4 by a cable 5 which extends to a hoist mechanism atthe ground surface.

The schematically illustrated setting tool 1 includes a cylinder 6. Thiscylinder has an upper portion 6a which houses an explosive charge 7 anda lower portion 6b which houses a piston 3. A conventional, explosivecharge igniting, electrical device 9 may be mounted in cylinder head cand actuated by an electrical signal transmitted through cable 5. Theactuation of ignition device 9 causes the detonation of the explosivecharge '7 which generates pressurized gas. This gas, in a wellrecognized fashion, will force piston S axially downwardly.

Packer portion 3, as schematically illustrated, may include upper slips10, upper slip expanding blocks 11, lower slips 12, and lower slipexpanding blocks 13. Slip expanding blocks 11 and 13 may function asabutnients engaging the upper and lower ends, respectively, of aradially expansible, resilient, and annular packer assembly 14.

Slips 1t) and 12, expander blocks 11 and 13, and the annular packerassembly 14 are slidably supported on a mandrel-like, central support15. An enlarged end a of mandrel 15 provides an annular abutment surface15b which engages the underside of the lower slips 12 as schematicallyshown.

As will be apparent, the imposition of converging forces on slips 1t)and 12 will tend -to cause these slips to move generally radiallyoutwardly while -convering toward each other so as to engage the wallofthe well bore 4. These forces will further tend to cause the radialexpansion of the packer assembly 14 into sealing engagement with thiswell bore wall.

For purposes of illustration, mandrel 15 is shown as extending throughthe force transmitting portion 2 of the apparatus and as being connectedwi-th the cylinder 6 of the setting tool 1.

Mandrel 15 is connected by an annular shoulder 16 to sleeve means 17.This sleeve means, which is coaxially related to mandrel 15, has anupwardly directed sleeve portion 13 extending from shoulder 16 and adownwardly directed sleeve portion 19 extending from shoulder 16.

As shown in FIGURES 4 and 5, sleeve portion 18 is of uniform innerdiameter and is radially spaced from the uniform outer diameteredmandrel 15 so as to define an upper or first, annular cylinder 20. Anannular piston 21 is slidably received within the cylinder and may beconnected by a cross-link 22 to a piston rod 23. Piston rod 23 extendsdownwardy from the setting tool piston 8. Cross-link 22 extends throughlongitudinal slots 15e and 15d in mandrel 15 so as to be axially orlongitudinally slidable and to be able to transmit longitudinal downwardmovement of the piston 8 through the wall of mandrel 15 to the piston21.

As shown in FIGURES 4 and 6, sleeve portion 19 includes an upper portion24 of uniform inner diameter which is radially spaced from mandrel 15 soas to define an upper or first, annular portion 25 of a second or lower,annular cylinder 26. As shown in FIGURES 4 and 7, lower portion 27 ofsleeve portion 19 has a uniform inner diameter exceeding the innerdiameter `of sleeve portion 24. Sleeve portion 27 is radially spacedfrom mandrel 15 and is connected to sleeve portion 24 so as to define asecond or lower portion 28 of second cylinder 26 which communicates withand defines an extension of the upper cylinder portion 25. In theillustrated arrangement, the inner diameter of sleeve portion 27 is thesame as the inner diameter of sleeve portion 1S.

A series of circumferentially spaced, longitudinally extending passages29, formed in shoulder 16, provide communication between the firstcylinder 20 and the upper or first portion 25 of the second cylinder 26.FIGURE 5 illustrates a representative arrangement of these passages incross section.

A second annular piston 3f? is slidably disposed in second cylinder 26.Piston 3f) includes an upper or first portion 31 which slidably andsealingly engages the upper if cylinder portion 25. Second piston 30additionally includes a second or lower portion 32 which slidably andsealingly engages second portion 28 of second cylinder 26 and isconnected with first piston portion 31.

With the cylinder 20, lpassages 29, and cylinder portion 25 above pistonportion 31 filled with fluid, the pistons 21 and 30 will be in fluidcoupled, force transmitting relationship. Downward movement of thepiston 21, caused by the explosively induced downward movement of thepiston 8, will thus induce downward movement of the piston 31.

The axial length of second portion 28 of the lower cylinder 26 exceedsthe axial length of the upper piston portion 31. Thus, the upper pistonportion 31 of the second piston 3f) will leave the upper cylinderportion 25 and enter the lower cylinder portion 28 during the downwardmovement of the piston 30.

As will be apparent, the first portion 25 of second cylinder 26 exposesonly the upper or first piston portion 31 to the pressure of fluid movedby the first piston 21 through the passages 29 into the cylinder portion25 while the piston portion 31 remains in sealing engagement with thecylinder portion 25. When the piston portion 31 has moved axiallydownwardly out of the cylinder portion 25 and into the cylinder portion28, both piston portion 31 and piston portion 32 are exposed to thepressure of fluid moved by the piston 21 through the passages 29 intothe cylinder 26.

Piston 31 will have a fluid reactive, piston head area equal to itsannular cross sectional area, i.e., the cross sectional area of thecylinder portion 25. Thus, with piston 31 in cylinder portion 25, thepiston 30 will have an effective iiuid reactive area equal to the crosssection of cylinder 20. Piston portion 32 will have an effective, fluidreactive, piston head area equal to its annular cross sectional arealess the annular, cross sectional area of the piston portion 31. Inother words, the effective liuid reactive, piston head area of thepiston portion 32 will equal the cross sectional area of the annularspace between the outer wall of the piston portion 31 and the inner wallof the sleeve portion 19. With piston 31 moved into cylinder portion 2S,the effective fluid reactive area of the piston 30 will -be equal to thecross sectional area of the piston portion 32, i.e. cylinder portion 28which, of course, is equal to the combined, piston head areas of thepiston portions 31 and 32.

As shown in FIGURE 8, the initial movement of piston 21 through theincrement X, caused by the explosively induced downward movement of thepist-on 8, piston rod 23, and cross-link 22, will result in movement ofthe piston 30 through a corresponding but larger increment Y. The ratioof increment Y to the increment X will be proportional to the ratio ofthe cross sectional area of the cylinder 20 to the cross sectional areaof the cylinder portion 25.

After the piston 30 has moved downwardly a sufiicient degree so as toenable the piston portion 31 to leave the cylinder portion 25 and enterthe cylinder portion 2S as shown in FIGURE 8, each increment of movementM of the piston 21 will be accompanied by a corresponding and equalincrement of movement N of the piston 3f). These equal rates of pistonmovement in the illustrated embodiment result from the equal crosssectional areas of the annular cylinder 20 and annular cylinder portion28.

An annular, sleeve-like portion 33 of piston 32 projects downwardly frompiston 32 and terminates in an enlarged lower end 34. End 34 provides anannular abutment shoulder 34a which engages the upper end of the upperslips 1f). Abutment 34a moves downwardly, relatively to mandrel 15, inresponse to relatively downward movement of piston 8 so as to cause thepreviously noted packer setting convergence of the expander blocks 11and 13 and the slips 10 and 12. However, owing to the differences ineffective, fluid reactive, piston head areas of the second piston 30during the initial and terminal portions of the downward movement ofthis piston, the initial convergence of the abutments 34a and 15b, asshown in FIG- URE 2, will occur at a relatively rapid rate withrelatively low applied force while the terminal portion of thisconverging movement will occur at a relatively slow rate but with agreater relatively applied force. Thus, during the initial part of thepacker setting, where little resistance to slip setting and packerexpansion is encountered and where the packer components are most freelymovable, the packer components are moved at an efficient, relativelyfast rate with an attendant relatively low applied force. During theterminal part of the setting operation shown in FIGURE 3, where greatersetting force is required, i.e. where it is necessary to expand thepacker into tight fitting sealing engagement with a well bore wall, thepacker components are moved with maximum applied force but at anattendant relatively slow rate.

As shown, annular piston 21 projects upwardly out of the upper open endof cylinder so as to extend upwardly away from the passages 29 and besubject to the pressure of well bore fluids surrounding the apparatus.Similarly, sleeve portion 33 of piston portion 32 projects downwardlyout of the lower open end of cylinder 26 so as to project downwardlyaway from the passages 29 so that piston 3f) will also be subject to thepressure of well bore fluid surrounding the apparatus.

Where, as in the illustrated embodiment, sleeve portions 18 and 19 areof uniform and the same diameter, the cross sectional areas of cylinderportions 2f) and 28 will be the same. In these instances the portions ofthe pistons 21 and 39, which are subject to the pressure of well borefluid, will have the same effective fluid reactive areas exposed to wellbore fluids. As a result, the pressure of well bore fluid exerted on theupper and lower ends of the pistons 21 and 30, respectively, will have asubstantially counter-balancing effect on these fluid coupled pistons.While the difference in elevation of the pistons 21 and 30 will providesome net, upward force resulting from the hydrostatic pressure of thewell bore fluids. this upward force will 'be of relatively minorconsequence.

Prior to describing the overall mode of operation of the apparatus,specic structural details of the force transmitting apparatus portion 2which are not illustrated in FIGURE l should be discussed with referenceto FIG- URE 4.

FIGURE 4 illustrates a representative manner in which the sleeve means17 may be associated with the mandrel 15 so as to provide the annularcylinders 20 and 26.

As shown in FIGURE 4, sleeve 17 is provided with the radially inwardlydirected, annular shoulder 16. Shoulder 16 has an internally threadedcoupling portion 35 which is threadably engaged with an externallythreaded coupling portion 36 formed on mandrel 15. An annular, radiallyoutwardly projecting mandrel shoulder 27 provides an abutment surfaceagainst which the lower edge of the shoulder 16 may come to rest, andthus be secured. As illustrated, the passages 29 may extend below theshoulder 16 and partially into the wall of the body of the mandrel 15 soas to terminate in communication with an annular opening 38 whichdefines the uppermost portion of the upper portion of the lower annularcylinder 26.

In order to insure that the pistons 21 and 30 remain in fluid coupledrelationship and are not adversely influenced by the pressure of wellbore fluids surrounding the apparatus, check valve means areincorporated in the apparatus. Such check valve means are adapted toallow well bore fluids to flow into each of the cylinders 2f) and 26 andare further adapted to prevent an outflow of fluid from these cylinders.

As shown in FIGURE 4, in the preferred embodiment of the forcetransmitting mechanism 2, the check valve means comprise first andsecond check valves 39 and 49 which comprise portions, respectively, ofthe pistons 21 and 30.

As shown in FIGURE 4, check valve 39 comprises an annular support ring41 to which is secured, by conven tional means, a generally annular andresilient, flexible seal 42. Seal 42 may be fabricated of resilientmaterial such as rubber or neoprene. Seal 42 includes a cylindricalportion 42a which is secured to the supporting ring 41 and a free-lipportion 42b having a generally downwardly converging, frustoconicalconfiguration. As illustrated, the lip portion 42h wipingly andsealingly engages the outer surface -of the mandrel 15. Support ring 41may be secured in an annular notched portion 43 on the lower end ofpiston 21 by conventional fastening means Ilot shown.

As illustrated, valve 39 is so mounted that the cylindrical portion 42aof flexible seal 42 is slightly radially spaced from the outer peripheryof the mandrel 15. As will be further noted by reference to FIGURE 4,the inner surface of the piston 21 may be substantially aligned with theinner surfaces of the seal portion 42a and the supporting ring 41 so asto define an annular channel 44 which is sealed from the cylinder 29below the head of piston 21 only by the lip portion 42!) of the flexibleseal 42. One or more radially extending ports 45 may be provided whichintersect the wall of the annular piston 21 so as to communicate withthe passage 44. In this fashion, a circuit of fluid communicationbetween the cylinder 20 and the exterior of the mechanism 2 is provided,with flow through this passage being controlled by the check valvefunctioning, seal lip portion 42h. As will be appreciated, with thedownwardly converging frustoconical configuration of the seal lipportion 42h, fluid will be prevented from flowing out of the cylinder 20by the seal lip 42b while fluid from the exterior of the tool may flowinto the interior of the `cylinder 2f! when the pressure of the wellbore fluid exceeds that of the coupling fluid contained within thecylinder 20. It will be apparent, of course, that fluid which enters thecylinder 2f) may also flow through the passages 29 so as to fill theupper portion 25 of the lower cylinder 26 if necessary.

Lower check valve 40 is structurally and functionally similar to uppercheck valve 39 and includes an annular support ring 46 and an annular,flexible and resilient seal 47 which may be fabricated from materialsuch as rubber or neoprene. Seal 47 includes a cylindrical portion 47awhich is secured to support ring 46 and an upwardly diverging, `free lipportion 47b which extends from the top of the seal portion 47a intowiping and sealing engagement with the inner wall of the sleeve portion27.

As illustrated, the cylindrical seal portion 47a, the periphery of themounting ring 46, and the periphery of the annular cylinder portion 32are spaced radially inwardly from the inner wall of the sleeve portion27 so as to define an annular passageway 48 which is adapted tocommunicate with the cylinder portion 28 above the piston 32. Fluid flowthrough this passageway is controlled by the seal lip portion 47h.Passageway 48 communicates with the exterior of the mechanism, i.e. withwell bore fluid, through passageway means such as the illustrated space49 between the lower edge of the sleeve portion 27 and the top of theenlarged sleeve portion 34. As will be appreciated, the upwardlydiverging character of the seal lip 47b will serve to prevent the flowof fluid out of the cylinder portion 28 while allowing well bore fluidfrom the exterior of the apparatus to flow through the passage 48 intothe cylinder portion 28.

With the check valve arrangement heretofore described, the apparatus maybe lowered into a fluid filled well ybore without any `coupling fluidbeing initially contained within the cylinders 26 and 26. Upon beingimmersed in the Well bore fluid, these cylinders will automatically fillin response to the pressure differentials existing across the seal lipportions 42h and 4711. This check valve arrangement also insures thatthe cylinder cavities will remain constantly fully filled so that therewill always exist an effective, pressure transmitting fluid couplingbetween the pistons 21 and 30.

In describing a preferred apparatus embodiment, several advantages ofthe invention have been demonstrated.

A foremost advantage of the invention resides in the manner in which theforce transmitting mechanism causes the setting components of anapparatus to move relatively rapidly and with relatively low appliedforce when the apparatus offers relatively low resistance to setting andthe setting components of the apparatus are most freely movable. Anespecially significant facet of the invention involves the manner inwhich the force transmitting mechanism automatically causes apparatussetting components to under a change in rate of movement, accompanied bya change in rate of applied force, so that while apparatus componentsare least freely movable and offer the greatest resistance to setting,they are moved at a relatively' low speed but with relatively greatapplied force.

Another significant aspect of the invention involves the manner in whichthe check valves associated with the tWo pistons of the forcetransmitting mechanism enables the apparatus to be lowered into a iiuidfilled well bore even though not containing coupling liuid. Onceimmersed in the fiuid, with there being a sufficient diierence inpressure between the well bore fluids and the cylinder interiorsefiective to open the check valves, well bore fiuid will automaticallyflow into and till the cylinders. This check valve arrangement will alsoinsure that the cylinders will remain filled throughout the operation ofthe apparatus so that the pistons of the force transmitting mechanismwill remain constantly in fluid coupled relationship.

An additional noteworthy aspect of the invention involves the manner inwhich the two piston of the force transmitting mechanism may be exposedto the well bore fluids but remain substantially pressure balanced.

It is also apparent that the force transmitting mechanism, Whilecharacterized by overall structural simplicity, Will also becharacterized by operational reliability.

While the invention has been described with reference to a preferredembodiment, it will be apparent that the utility of the forcetransmitting mechanism is not limited to the setting Of the illustratedpacker embodiment. It will also be apparent that the invention is notlimited to the illustrated dimensional relationships of the variouspiston and cylinder components of the force transmitting mechanisms, tothe illustrated piston, cylinder, configurations and seal to the use ofa multi-stepped piston having two reactive areas, or to the use of thespecically illustrated check valves.

In describing the invention, various apparatus elements, normallymulti-component in character, have been shown as unitary assemblies soas to avoid structural complexity which might obscure the invention.

Those skilled in the art and familiar with the disclosure of theinvention may well recognize additions, deletions, substitutions andmodifications which would be within the purview of the invention asdefined in the appended claims.

I claim:

1. An apparatus for use in a well bore, said apparatus comprising:

force generating means including an actuating means and operable withina well bore to move said actuating means;

a mechanism to be actuated within said well bore; and

force transmitting means operatively disposed between said actuatingmeans and said mechanism and including first means movable in responseto movement of said actuating means, second means movable in response to-movement of said rst means and adapted to actuate said mechanism, andcoupling means operably connecting said first and second means andIadapted to cause said second means to initially move at a first ratemore rap-id than the rate of movement of said first means and thereaftermove at a second rate slower than said first rate, said second meansWhile moving at said second rate transmitting greater force to saidmechanism than when moving at said first rate.

Cil

2. An apparatus as described in claim 1: wherein said actuating meanscomprises actuating piston means; wherein said force generating meansincludes cylinder means housing said actuating piston means, andexplosive means contained within said cylinder means and adapted togenerate gas within said cylinder means so as to move said actuatingpiston means; wherein said mechanism includes radially expansible packermeans, and axially movable abutment means adapted to axially compresssaid packer means to effect the radial expansion thereof: wherein saidfirst means of said force transmitting means comprises first pistonmeans: wherein said second means of said force transmitting meanscomprises second piston means having first and second, fiuid reactive,piston head areas; and wherein said coupling means includes firstcylinder means in which said first piston means is slidably received,second cylinder means in fiuid communication with said first cylindermeans and in which said second piston means is slidably received, saidsecond cylinder means having a first portion adapted to expose only saidfirst fiuid reactive, piston head area of said second piston means tothe pressure of fluid urged by said first piston `means from said firstcylinder means into said second cylinder means during the initial move-Kment of said second piston means, and said second cylinder meansfurther having a second portion adapted to expose both the first andsecond, fiuid reactive, piston head areas of said second piston means tothe pressure of tluid moved by said first piston means from said firstcylinder means into said second cylinder means during the terminalmovement of said second piston means. 3. An apparatus -as described inclaim 2 including: first check valve means adapted to prevent fiuid fiowout of said first cylinder means but allow well bore fiuid surroundingsaid apparatus to fiow into said first cylinder means; and second checkValve means adapted to prevent fiuid ow out of said second cylindermeans but allow well bore fiuid surrounding said apparatus to fiow intosaid second cylinder means. 4. A force transmitting mechanism for use ina well bore, said mechanism comprising:

first piston means; second piston means having at least first andsecond,

fluid reactive, piston head areas; first cylinder means in which saidfirst piston means is slidably received; second cylinder means in tiuidCommunication with said first cylinder means and in which said secondpiston means is slidably received; said second cylinder means having afirst portion adapted to expose only said first fiuid reactive, pistonhead area of said second piston means to the pressure of uid urged bysaid first piston means from said first cylinder means into said secondcylinder means during one portion of the movement of said second pistonmeans; and said second cylinder means further having a second portionadapted to expose both the first and second, fiuid reactive, piston headareas of said second piston means to the pressure of fluid moved by saidrst piston means from said first cylinder means into said secondcylinder means during another portion of the movement of said secondpiston means; one of said piston means being adapted to move in responseto a force applied thereto within a well bore; the other of said pistonmeans being adapted to trans- -mit force to means to be actuated withinsaid well bore. 5. A mechanism as described in claim l including: firstcheck valve means adapted to prevent Fluid flow out of said firstcylinder means but allow well bore Huid surrounding said mechanism to owinto said rst cylinder means; and second check valve means adapted toprevent uid ow out of said second cylinder means but allow well bore uidsurrounding said mechanism to How into said second cylinder means. 6. Aforce transmitting mechanism for use in a well bore, said mechanismcomprising:

mandrel means; sleeve means having portions radially spaced from saidmandrel means to define with said mandrel means, in consecutive, axiallyspaced relationship,

first, annular cylinder means, and second, annular cylinder means;passage means providing7 fluid communication between said rst `andsecond cylinder means; rst, annular piston means axially slidable insaid first,

annular cylinder means; and second, annular piston means axiallyslidable in said second, annular cylinder means; said second, annularcylinder means having a iirst, annular portion facing and communicatingwith said passage means, and a second, annular portion having a crosssectional area exceeding that of said first, annular portion anddefining an extension of said second, annular portion leading away fromsaid passage means; and said second, annular piston means having afirst, annular portion slidable within said nrst, annular portion ofsaid second, annular cylinder means in substantially sealing engagementtherewith, and a second, annular portion slidable within said sec- 0ndannular portion of said second, annular cylinder means in substantiallysealing engagement therewith, the axial length of said first, annuarportion of said second, annular piston means being such that, prior tothe end of the axial movement of said second, annular piston means awayfrom said passae means, said rst, annular portion of said second,annular piston means leaves said first, annular portion of said second,annular cylinder means and enters said second, annular portion of saidsecond, annular cylinder means;

said first, annular piston means being adapted to move in response to aforce applied thereto within a well bore;

said second, annular piston means being adapted to transmit force tomeans to be actuated within said well bore.

7. A mechanism as described in claim 6:

wherein said rst, annular piston means has a portion projecting out ofsaid rst annular `cylinder means, extending in one direction away fromsaid passage means, and subject to the pressure of well bore fluidsurrounding said mechanism;

wherein said second portion of said second annular piston means has aportion projecting out of said second portion of said second, annularcylinder means, extending in a direction opposite to said one directionaway 'from said passage means, and subject to the pressure of well borefluid surrounding said mechanism; and

wherein the cross sectional area of said rst, annular cylinder means issubstantially the same as the cross sectional area of the second portionof said second, annular cylinder means.

S. A mechanism as described in claim 7:

wherein said first, annular piston means includes rst, annular flexibleseal means disposed in slidable and sealing engagement with said first,annular cylinder means and adapted to allow well bore fluid surroundingsaid mechanism to flow into said rst cylinder means and further adaptedto prevent a flow of fluid out of said first cylinder means; and

wherein said second portion of said second, annular piston meansincludes seco-nd, annular exible seal means slidably and sealingengaging said second portion of said second, annular cylinder means andadapted to allow well bore fluid surrounding said lmechanism to ow intosaid second, annular cylinder means and further adapted to prevent -a owof fluid out of said second cylinder means.

References Cited by the Examiner UNTED STATES PATENTS 2,881,841 4/1959Page 166-212 3,l38,207 6/1964 Peppers 166-63 3,193,013 7/1965 Whiteside166-63 3,266,575 8/1966 Owen 166-63 CHARLES E. OCONNELL, PrimaryExaminez'.

I. A. LEPPNK, Assistant Examiner'.

1. AN APPARATUS FOR USE IN A WELL BORE, SAID APPARATUS COMPRISING: FORCEGENERATING MEANS INCLUDING AN ACTUATING MEANS AND OPERABLE WITHIN A WELLBORE TO MOVE SAID ACTUATING MEANS; A MECHANISM TO BE ACTUATED WITHINSAID WELL BORE; AND FORCE TRANSMITTING MEANS OPERATIVELY DISPOSEDBETWEEN SAID ACTUATING MEANS AND SAID MECHANISM AND INCLUDING FIRSTMEANS MOVABLE IN RESPONSE TO MOVEMENT OF SAID ACTUATING MEANS, SECONDMEANS MOVABLE IN RESPONSE TO MOVEMENT OF SAID FIRST MEANS AND ADAPTED TOACTUATE SAID MECHANISM, AND COUPLING MEANS OPERABLY CONNECTING SAIDFIRST AND SECOND MEANS AND ADAPTED TO CAUSE SAID SECOND MEANS TOINITIALLY MOVE AT A FIRST RATE MORE RAPID THAN THE RATE OF MOVEMENT OFSAID FIRST MEANS AND THEREAFTER MOVE AT A SECOND RATE SLOWER THAN SAIDFIRST RATE, SAID SECOND MEANS WHILE MOVING AT SAID SECOND RATETRANSMITTING GREATER FORCE TO SAID MECHANISM THAN WHEN MOVING AT SAIDFIRST RATE.